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Replacing chamois gasket


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I'm in the process of fixing up a Lachenal tutor EC that I bought off eBay. So far, I've replaced about half the valves (the ones that were stiffest or most curled), replaced one pad (that was misaligned to begin with and wasn't sealing at all), patched a few small holes in the bellows, and reglued one of the pillars that had come loose. I've been doing all this a bit at a time, which means I've removed and replaced the ends several times. The chamois gasket was worn very thin when I got it, and doesn't seem like it will last much longer. It still seems to be making a reasonably good seal, but I don't know how much more "roughing up" it can take. So I suppose I'll need to replace it at some point. I've been following Dave Elliott's maintenance manual, but this doesn't seem to be covered in there. And so I have questions.

 

1. I gather from other threads here that any old chamois will work, but thicker is better? Any particular thickness I should be aiming for?

 

2. How exactly do I do this? How do I figure out what size and shape to cut, how do I fit it into place, what kind of glue should I use, etc.? I've been looking around for instructions, but haven't found any. I guess it might be easy to figure out, but I don't want to take the old gasket off only to realize that I have no idea what I'm doing.

 

3. The chamois strips along the partitions between the reed chambers seem to be in good condition, but it looks like if I replace the worn-out outer gasket with something thicker, the inner strips will no longer be high enough to make a good seal. Is that a reasonable suspicion? What do I do if that happens?

 

4. Anything else I need to be careful about?

 

Thanks in advance for your help. :)

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I have successfully done this using chamois sold for car washing purposes. Picking one one out looks a reasonable thickness.

 

Take careful note if the pan seems a little loose and plan to shim with extra thickness under the new gasket face (not over).

 

The glue I used was "Elmer's School Glue", the washable gel type. You really only need to hold the gasket in place, and a light duty adhesive like this means you can reverse relatively easily if a mistake is made.

 

When you have removed the old gasket (which includes carefully scraping off the bulk of the old glue), check the bolt mounting plates. Now is the time to do any work on those, the screws can be loose (don't overtighten). Any rust bumps etc will mess up your gasket job.

 

Cut strips slightly wider than you will need, make a partly mitered cut on one end, and start the gluing process from a corner. Glue the edge only (roughly 1/4" edge of the bellows frame) in short sections and work the chamois strip around, extra care to get the corners (120 deg) nicely done. Not too much glue as you don't want to harden the chamois.

 

When this is done, you can start marking and triming the corners as necessary to bring the chamois down into the frame. I use a strip of wood cut to fit into the frame to set on top of the blocks so that I can mark and trim the bottom edge. Once trimmed, the face is then lightly glued in, making sure the corners will provide a good seal. Best to mark and trim one section at a time as the chamois tends to stretch a bit. Don't forget to put in any shim sections, if required, before you glue the faces down.

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Thanks, apprenticeOF - this is really helpful. The reed pans don't seem loose at all, so I don't think I'll need to fit a shim around the edge of the frame. I guess I could put a shim on top of the support blocks to adjust the height of the reed pan if necessary? Has anyone ever found it necessary to do this?

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When using car wash chamois look for one with consistent thickness. 1mm thick is very useable, .5 is a little thin. If you can't find one with sufficient consistency to get a long strip which will go right around it is permissible to use two pieces. Car wash chamois is not necessarily best quality, look at the surface finish, less good chamois will pill a little.

 

Replacing the chamois at the top of the partitions at the same time makes a lot of sense.

 

The method above looks like it would work, but for what it's worth I place the chamois inside the frame first, allow the glue to go off, then stretch it over the outside rim. This makes the trimming process easier. Note that none of my bellows are replacements and I fit the chamois before fitting the leather end run. This makes it easy to trim the chamois to size at the top edge.

 

The join, which I place on a side rather than a corner, needs care, stretching the chamois over the corners wants to pull it away from the join. Consequently when I have gone around placing the material inside the frame, and I get back to the start, I cut the material straight up the side and then at 45 degrees towards the join as it crosses the edge and this sits nicely when the material is stretched over the edge.

 

Shimming the support blocks is a normal process. Use something hard, paper or card, not leather. Taking the the blocks off and placing them in a revised position is probably better practice.

 

Chris

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Is that something like a pizza cutter? Can you suggest

something suitable?

Ta,

Malcolm

 

 

Similar to a pizza cutter, Rotary Cutters are very effective as they do not tend to drag the 'material' like a knife can.

 

I use a 'wallpaper trimmer', available in the wallpapering tools section of most DIY stores, which can be somewhat cheaper and just effective as those found in 'Craft' stores.

 

Geoff

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...fabric stores have these rotory cutters as they are a heavily relied on item with quilters--cutting all those tiny pieces to sew together. And in fact look at the cutting mats that are used for the backing to cut on--they are resistant to continued cuts without falling apart.

Edited by shelly0312
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Why is Chamois used for this job ? It is a very porous material to use as a gasket. I feel that one of the more 'Airtight' leathers might be more appropriate.

 

This is a job I am going to have to do on one of my Concertinas... anybody use a different material for this?

 

Interesting that this comes up... I have for a long time pondered with trying this here one:

 

http://www.hylomar.com/

 

Hylomar Universal Blue reads like it was designed to do the job; has anyone ever tried it? Well, it's certainly far from traditional, but that shouldn't necessarily be a reason for or against it...

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Cetainly not that one. I use it on antique engines all the time; it forms a thick goo once the solvent evaporates but does not really set, as they say. It gets everywhere you allow it to and would not come off the woodwork once spread about. Just try getting it off your hands later on, for starters. And unless you put some parting agent on one side you'd risk doing damage pulling the components apart. Brilliant stuff in its place (rumoured to be used by Rolls Royce) but not here, I'd suggest.

 

The business of separating the parts later might well be your main problem with liquid gasket sealants.

 

You could try a layer of paper; so: use RTV silicon perhaps (bathroom sealant), drop a sheet of newspaper over the siliconed end, put on the end but loosely, let it cure in position, then later wind all the bolts down the last turn, compressing the cured silicone.

 

Don't think I'll be trying that on my aeola, although if someone comes up with a more convincing scheme I might be tempted.

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Cetainly not that one. I use it on antique engines all the time; it forms a thick goo once the solvent evaporates but does not really set, as they say. It gets everywhere you allow it to and would not come off the woodwork once spread about. Just try getting it off your hands later on, for starters. And unless you put some parting agent on one side you'd risk doing damage pulling the components apart. Brilliant stuff in its place (rumoured to be used by Rolls Royce) but not here, I'd suggest.

 

The business of separating the parts later might well be your main problem with liquid gasket sealants.

 

You could try a layer of paper; so: use RTV silicon perhaps (bathroom sealant), drop a sheet of newspaper over the siliconed end, put on the end but loosely, let it cure in position, then later wind all the bolts down the last turn, compressing the cured silicone.

 

Don't think I'll be trying that on my aeola, although if someone comes up with a more convincing scheme I might be tempted.

 

Great, thanks for the info! I remember working with Hylomar very many years ago, and it did the job it was supposed to do back then perfectly - but obviously I never got to the reversal part. Sounds like a piece of overpromising marketing to me...

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Err.. yes I have used that Blue silicone stuff for putting antique motorbike engine parts together and even then you have to be very carefull that none comes off on the insides and ends up blocking a vital oilway .

 

I was more thinking of using something close to the original Chamois... I have some very airtight 1mm leather that I use for making Bagpipe Bellows... but maybe it could be more tricky to pull (stretch) around the corners.

 

I am going to try using a sheet of (airtight) Foam EVA... very thin stuff, just to cover the whole gasket face.. bolt it up and see if there is a great improvement in airtightness and thus 'compression'. If this works then I will look at replacing the Chamois properly either with new Chamois or the leather that I have.

 

Yes this is on my 58 Maccann Aeola so I want to do it well.

 

I've been thinking to get a cheap Stethoscope so I can listen for air leaks and localise the problem... it would appear to be less messy than spitting on the suspect area as suggested in David Elliots book.

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Here is a little tip for holding the Chamois. Fix some 120 0r 160 grit wet and dry on the under side of your straight edge with double sided tape. This will hold the Chamois whilst you are cutting it. We sell Rotary Cutters and manufacture Wall Paper Cutters.www.proopsbrothers.com.

P S Grit side down of course

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Interesting website with lots of usefull stuff Nick.

 

Well, I have made my 'airtight' foam sheet test, putting this across the bellows and bolting the ends back on.... no difference to the slight leaking.... so that should rule out any 'End' caused leak. Therefore it must be down to the 95 year old Bellows.

The Bellows looks fine.. not too worn anywhere, no mishapen corners, not stiff or dry (looking).... Hmmm ??? Will try the light bulb inside the bellows , in a darkened room and look for tiny holes... maybe the gussets are just a little porous.

 

Now where can I get a cheap Stethoscope ???

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I find the wet the lips, open the mouth, squeeze the bellows method of detecting leaks fairly effective. Then you can resort to the spit method or your favorite alternative to absolutely localize the leak.

 

Chamois leaks can be very subtle. In certain instances I've gone over bellows and pads numerous times only to change the chamois bellows seal and voila', problem solved.

 

Carroll Concertinas uses a thin, dense foam matt laser cut for a one piece seal for chambers and a similar material for the bellows seal. The foam works well but at the Carroll factory we have the advantage of fitting everything to newly manufactured surfaces.

 

Chamois seems to stay resiliant and resist deterioration. In many of the 100 year old concertinas I've refurbished the chamois could be renewed and still provided a good seal. I have not been as impressed with the leather that Wheatsone went to from the mid 1930s on. In my experience in a number of cases it had become crumbly and very difficult to keep intact to lift the inside edge when shimming the bellows seal.

 

One disadvantage of working with chamois is that it will suck up any inadvertant glue spill and that can compromise its compression sealing properties.

 

Greg

 

Spelling edited. Grammar edited.

Edited by Greg Jowaisas
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I find the wet the lips, open the mouth, squeeze the bellows nethod of detecting leaks fairly effective. Then you can resort to the spit method or you your favorite alternative to absolutely localize the leak.

 

Cmamois leaks can be very subtle. In certain instances I've gone over bellows and pads numerous times only to change the chamois bellows seal and voila', problem solved.

 

Carroll Concertinas uses a thin, dense foam matt laser cut for a one piece seal for chambers and a similar material for the bellows seal. The foam works well but at the Carroll factory we have the advantage of fitting everything to newly manufactured surfaces.

 

Chamois seems to stay resiliant and resist deterioration. In many of the 100 year old concertinas I've refurbished the chamois could be renewed and still provided a good seal. I have not been as impressed with the leather that Wheatsone went to from the mid 1930s on. In my experience in a number of cases it had become crumbly and very difficult to keep intact to lift the inside edge when shimming the bellows seal.

 

One disadvantage of working with chamois is that it will suck up any inadvertant glue spill and that can compromise its compression sealing properties.

 

Greg

 

Thanks Greg,

for these good practical points. It is possible that my test using thin sheets of EVA foam sandwiched between the pallet boards and the old chamois gaskets was inconclusive. I will take your advice and replace the Chamois.

 

With a Duet of medium size I want all the air I can get... for the bigger chords and thus good compression for 'attack'.

 

Cheers,

Geoff.

Edited by Geoff Wooff
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